Generally, a pedal body at a pedal for the bicycle, as disclosed in the U.S. Pat. No. 2,542,548 and Swiss Pat. No. 279,819, has foot bearing portions provided at both sides of a pedal shaft and in parallel thereto.
The foot bearing portions are disposed linearly in parallel to the pedal shaft while a cyclist places on the pedal body his foot at the first through fifth metatarsi arranged at the heads thereof in an arcuate shape, so that the head of the fifth metatarsus, even when that of the first metatarsus is placed on the foot bearing portion, will come off therefrom.
A bony framework of the human foot comprises 26 bones in combination, which are roughly divided from an aspect of construction into the tarsi, metatarsi, and phalanges. The tarsi are composed of seven bones of the calcaneous, talus, cuboid, navicular, and first through third cuneiforms in a tight combination, the metatarsi comprising five bones corresponding in number to the toes and extending frontward from the group of tarsal bones and disposed laterally of the foot, the phalanges extending frontward from the metatarsi and comprising 14 bones of the first phalange for the big toe comprising two bones and the second to fifth phalanges for other toes comprising three bones respectively.
From the aspect of the bony framework and function, the calcaneous, cuboid, first to third cuneiforms, first and third metatarsi, and first to third phalanges, are included in a first group, and the talus, navicular, fourth and fifth metatarsi, and fourth and fifth phalanges, are included into a second group.
The bones in the first group bear a body weight and function to kick the ground when a person steps forward and those in the second group function to balance his body for a smooth walk.
In view of the above, the conventional pedal creates a problem in that the head of the fifth phalange comes off from the foot bearing portion even when that of the first phalange contacts therewith, so that the cyclist cannot transmit his treading force effectively to the pedal body, and his pedalling operation is unbalanced and unsmooth. As a result, it is difficult for him to get a larger treading force by effective use of energy because his foot is readily fatigued.